Articles of manufacture made of polyurethane foam which generally are of the type considered herein, and apparatus for processing the foamed plastic material are known. Representative examples include U.S. Letters Pat. Nos. 2,836,228 (Dahle), 3,009,848 (Simon), 3,186,271 (Kaiser), 3,222,697 (Scheermesser), 3,258,791 (Kaplan), 4,064,578 (Yamada), 4,070,719 (Morgan), 4,106,139 (Southard) and 4,207,636 (Ceriani).
Referring more specifically to the prior art, Dahle discloses a foam cushion embodying a foamed elastomer, such as natural rubber latex, vinyl foam and polyurethane. The cushion comprises a body including a pair of outer foam sections and a frame comprised of a plurality of bonding layers. The outer surfaces of the cushion are flat and the confronting faces of the foam sections are contoured, each to provide a plurality of opposing hills and valleys.
The Simon patent relates primarily to apparatus for cutting slabs of foamed plastic with devices comprising a plura1ity of knives or hot wires mounted at regular distances from one another. Cutting may be carried out when the slab of foamed plastic is passed between rollers and when the slab of foamed plastic is under compression. The Kaiser patent, like the Simon patent, discloses a manner of processing a slab of foamed plastic for production of an article having a regular or irregular surface contour.
The Scheermesser, Southard and Ceriani patents are each directed foamed articles of manufacture having a surface profile created by apparatus, such as a hot wire. Cutting the profile may be accomplished by relative movement of a block of foam and the hot wire. The block of foam is cut by an undulation of the hot wire to produce two or more substantially identical surfaces. In Scheermesser the surfaces comprise a plurality of parallel ribs and grooves, having a rectangular, triangular, trapezoidal or arcuate cross section, for example: Kaplan discloses a pad having a surface formed by a plurality of protuberances and cavities.
The cushion of the Yamada patent, in appearance, generally duplicates the pad disclosed by Kaplan. The cushion and pad of these patents includes surfaces somewhat likened to an "egg crate" convolute which is supported by a base, such as the mattress of Kaplan so that the contoured surface is exposed.
The Morgan patent relates to a cushioning element having a plurality of intersecting grooves formed in a surface of the body.